Slide-valve mechanism for steam-engines.



PATENTED MAR. 28, 1905.

F. B. SMITH. I SLIDE VALVE MECHANISM FOR STEAM ENGINES:

APPLIOA T10N FILED APR. 30, 1904.

4 SHEETS-8HEET 1.

W A n PATENTED MAR. 28, 1905. F. E. SMITH.

SLIDEVALVE MECHANISM FOR STEAM ENGINES. I

APPLIUATIOR FILED APB.30,1904.

4 SHEETSBHEET 2.

INVENTOH Ban/a3 film it]:

No. 786,060. PATENTED MAR. 28, 1905.

' P. E. SMITH.

SLIDE VALVE MECHANISM FOR STEAM ENGINE S.

APPLIGATION FILED APR.3,0,1904.

4 SHEETS-SHEET 3.

WITNESSES: IN VE N TO/i- No. 786,060. PATENTED MAR. 28, 1905. F. E.SMITH. SLIDE VALVE MECHANISM FOR STEAM ENGINES.

APPLICATION FILED 111 3.30, 1904.

4 SHEETS-SHEET 4.

F5 3 30 473 I? "79 29 L' '5, Zl-

llllll' W/TNESSES: 3? I INVENTOH '53 1 61 i I fiankEJnziZlo 1 PatentedMarch 28, 1905.

PATENT OFFICE.

FRANK ELI SMITH, OF MUNNSVILLE, NEW YORK.

SLIDE-VALVE MECHANISM FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 786,060, dated March28, 1905.

Application filed April 30,

T0 at whom it may concern.-

Be it known that I, FRANK ELI SMITH, a citi- Zen of the United States,and a resident of Munnsville, in the county of Madison and State of NewYork, have invented a new and Improved Slide-Valve Mechanism forSteam-Engines, of which the following is a full, clear, and exactdescription.

This invention relates to slide-valve mechanism for engines, but moreespecially to slidevalve mechanism for locomotive-engines.

The principal object of the invention is to provide a slide-valvemechanism comprising separate inlet and exhaust valves and means for reducing the stroke of the inlet-valve without diminishing the stroke ofthe exhaustvalve, and thereby reducing the rate of exhaust from theengine-cylinder.

As is well known to persons skilled in the art, it is customary instarting a locomotiveengine having a load attached thereto to set theinlet-valve for its full stroke, so as to admit to the cylinder of theengine upon each stroke of the valve the maximum amount of steam, thisbeing necessary to overcome the inertia of the load and to set theengine and its load in motion. After the engine has developed some speedthe stroke of the inlet valve is gradually cut down, because the maximumamount of steam which is admitted by the valve when operating at fullstroke is no longer necessary and is, in fact, objectionable, because itcannot be exhausted with sufficient rapidity to obtain the best effectsfrom its expansion. In the engines now in general use upon railroads themechanism by which the steam is admitted to the cylinder and allowed toescape therefrom is such that when the stroke of the inlet-valve isreduced to lessen the amount of steam admitted upon each stroke thereisasimilar reduction of the stroke of the exhaust-valve, and for anyreduction of the amount of steam admitted to the cylinder there is acorresponding reduction of the exhaust.

The reduction of the exhaust when the inlet of steam into th" cylinderis reduced is exceedingly undesirable, for the reason that the steam infront of the piston during its stroke 1904. Serial No. 205,715.

I opposes a considerable resistance to the movel ment of the pistonunder the influence of the steam behind it, and it is exceedinglydesirable to reduce this resistance opposed to the piston hy' theunexhausted steam to an amount which is just sufficient to serve'as acushion between the piston'and the cylinder-head. In the engines now ingeneral use the resistance which the unexhausted steam opposes to theforward movement of the piston uponeach stroke when the engine istraveling at a high speed is sometimes as high as thirty-five per cent.of the pressure of the steam expanding behind the piston, and hence onlyabout sixtyfive per cent. of the pressure of the expanding steam iseffective upon, the piston. Consequently if means were provided foreffecting the complete exhaust of the steam in front of the piston, soas to allow the full effect of the steam behind the piston to beobtained, an increase of approximately fifty per cent. of the efliciencyin the engine Would result. It is, however, impossible with an enginehaving a reciprocating piston to dispense with all resistance fromunexhausted steam in the cylinder, as it is necessary to provide acushion between the piston and the cylinder-head to avoid injury to thecylinder-head from the violent and unopposed stroke of the piston: butthe necessary cushion between the piston and cylinder head is affordedby a much smaller quantity of unexhausted steam than now remains in thecylinder during its stroke, and it is desirable to provide for theexhaust of the steam to the minimum amount requisite to cushion thestroke sufliciently to prevent injury to the cylinder-heads.

The mechanism by which I accomplish the object above stated consists,essentially, of a separateinlet-valve and exhaust-valve for each engine-cylinder, independent mechanism, preferably comprising linkmotiondevices for reciprocating said valves, and mechanism for reversing thestroke of both valves simultaneously, which permits the reduction of thestroke of the inlet-valve without affecting in any way the stroke of theexhaust-valve.

One form in which the invention may be embodied is hereinafter describedin detail,

and the novel features thereof are particularly pointed out in theappended claims, it being understood that changes in the form,proportions, and in the mode of assemblage of the elements described maybe made without departing from the spirit of the invention orsacrificing the advantages thereof.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar characters of reference indicatecorresponding parts in all the views.

Figure 1 is a View in side elevation of a loeomotiveengine provided withthe valve mechanism forming the present invention. Fig. 2 is a view,partly in elevation and partly in section, of one of thelocomotive-cylinders, the inlet and exhaust-valves associated therewith,and the mechanism for imparting movement to the valves. Fig. 3 is a planView of the structures shown in Fig. 2. Fig. 4 is .a plan View of thevalve-seat, showing the inlet and exhaust ports. Fig. 5 is a bottom planview of the inlet and exhaust valves. Fig. 6 is a longitudinal sectionalview through the valves and valve-seat, showing the relations of theseparate inlet and exhaust valves. Fig. 7 is a transverse sectionthrough the inlet and exhaust valves and the valve-seat. Fig. 8 is adetail view showing the internal structure of the locking mechanism bywhich the exhaust-valve-reversing mechanism is held in fixed positionduring the adjustment of the inlet-valve-operating mechanism to reducethe stroke of the inlet-valve, the locking mecl anism being shown inoperative position. Fig. 9 is a plan view of the structures shown inFig. 8. Fig. 10 is a view of the locking mechanism shown in Fig. 8, themechanism being shown in inoperative position. Fig. 11 is a sectionalview upon the line 11 11 of Fig. 8 looking toward the left, and Fig. 12is a sectional view upon the line 12 12 of Fig. 8 looking toward theright.

Referring to the drawings, 1 designates a cylinder of alocomotive-engine having a steam-chest 2 at the top thereof, as usual.

3 designates the valve-seat within the steamchest, and 4 4 designate theinlet-ports in the valve-seat 3, the inlet-ports 4 leading into thepassages 5, which extend to the front and rear ends of the cylinder, asshown in Fig. 2. The passages 5 are continued upward and terminate inexhaust-ports 6 near the middle of the valve-seat 3, and extendingtransversely of the valve-seat between the exhaust-ports .6 from thecylinder is the usual opening 7,

through which the exhaust-steam passes to the outer air.

The inlet-valve which cooperates with the inlet-ports 4 is designated 8and has the in terior thereof cut out to provide space for thereciprocation of the exhaust-valve 9, which cooperates with the exhaustports 6 and connects theseports alternately with the opening 7 Motion isimparted to the inlet-valve 8 by the reciprocations of a hollowvalve-rod 10, which works in a gland 11 in the end of the steam-chestand carries a U-shaped bracket 12, the ends of which engage with notches13 in the sides of the inlet-valve, as best shown in Figs. 3 and 5. Theexhaust-valve is reciprocated by means of a valve-rod 14, workingthrough the hollow rod 10 and through a gland or stuffing-box 15,provided at the outer end of the said hollow Valve-rod. The hollowvalve-rod 10 is connected at its rear end with a frame 16, in which thegland 15 works, and the frame 16 is connected at its rear extremity witha rocker 17, carried by a shaft.18, journaled at the rear of therock-shaft box 19. The valve-rod 14 is connected with a rocker 20,mounted on a shaft 21, journaled in the forward end of the rock-shaftbox 19. The rockers 17 and 20 are connected with sliding blocks 22 and23, respectively, said blocks being arranged for sliding movement inlinks 24 and 25, respectively. The saddle of the link 24 is connectedwith the curved arm 26 of a bell-crank lever mounted on a shaft 27 andhaving the other arm, 28, extended upward to connect pivotally with alink 29, which is connected at its other end with the reversinglever rod30. The saddle of the link is connected with the arms 31 of a bell-cranklever mounted on the shaft 32 and having the other arms, 33, thereofpivotally connected with a link 34, which is connected at its other endwith a sliding casing 35, mounted for reciprocation upon a bed 36 andcontaining locking mechanism, as hereinafter described. The arms 28 and33 of the bell-crank levers, which serve as link-lifters, bear the ratioof two to one in length, for reasons that will hereinafter ap pear.

To give the desired rocking movement to the links 24 and 25, twoeccentrics 37 and 38 are mounted upon the driving-axle 39 andeccentric-straps 37 and 38, respectively. The pivoted rods 42 and 43connect the upper and lower ends, respectively, of the link 24 with thetwo eccentric-straps and 41, respectively, and similar rods 44 and 45connect the upper and lower ends of the link 25 with the sameeccentrics. In consequence of this arrangement the two eccentrics 37 and38 impart oscillatory movement in opposite directions to the links 24and 25 simultaneously.

-The casing 35, which is mounted for sliding movement upon the bed 36and is connected, by means of the link 34, with the arm 33 of thebell-crank lever, by which the link 25 is raised and lowered, contains anovel locking mechanism, which is adapted to operate automatically whenthe casing 35 is moved to either end of the bed 36 by shifting thereversing-lever 46, to which the rod 30 is attached. The rod 30 has aframe 47 secured thereon, as best shown in Fig. 9, the frame 47surrounding the casing 35 and affording space for the movement of theframe for a consid-' erable distance without causing it to engage thecasing. Extending transversely through the casing 35 and secured in theframe 47 and rod 30 is a bolt or pin 48, and to provide for the movementof the bolt or pin 48 without shifting the casing 35 a slot 49 is formedin each side of the casing.

1n the interior of the casing 35 a lockingblock 50 is arranged forvertical sliding movement in ways 51 in the middle of the casing. Thisblock 50 is provided at the bottom with a downward projection 52, whichpreferably contains a small roller 53, which is adapted to travel alongthe bed 36 to prevent wear of the projection when the casing 35 is movedto and fro upon the bed. The block 50 is normally depressed by a spring54, arranged in an opening 55 in the block and abutting at its upper endagainst a stud 56, formed upon the rear wall of the casing, as bestshown in Fig. 12. At either side of the locking-block 50 a smallbell-crank lever 57 is mounted upon a shaft 58. These levers 57 are eachprovided with an approximately horizontal arm 59, terminating in a disk60, which works in a recess in the face of the locking-block 50, asshown. Each bell-crank is also provided with an approximately verticalarm 61, presenting a concavity 62 for engagement with the pin or bolt48. hen either of the concavities 62 is engaged by the pin or bolt 48,the bell-crank lever upon which the concavity is formed will be tiltedor rocked into the position shown in Fig. 10 and the locking-block 50will be raised in the casing. hen, however, the pin or bolt 48 does notengage with either of the bellcranks 57, the locking-block is depressedby the spring 54 and the projection 52 at the bottom thereof will engagewith one of two slots or recesses 63, formed for that purpose in the bed36, over which the casing slides. These slots or recesses 63 are soplaced in the bed 36 that when the projection 52 engages with either thecasing must be at the limit of its movement toward one end of the bed,as clearly shown in Fig. 8.

In addition to the locking-block 50 and the parts cooperating therewith,as above described, the casing 35 contains two springpressed bolts 64,arranged at opposite ends of the casing and adapted to enter openings65, provided in the bed 36, as best shown in Fig. 10. Each of thespring-pressed bolts 64 has the stem or shank thereof extended upwardalmost to the top of the casing 35, and a bar 66 is pivotally connectedat its ends with each of the bolts 64. pressed bolts 64 aresuch thatwhen the bar 66 is raised above the slots 49 throughout its entirelength the two bolts 64 will be retracted into the casing 35 and willnot engage with either of the openings 65, provided in the bed 36, uponwhich the casing slides.

To make the operation of the valve mech- The dimensions of thespringanism above described clear to persons skilled in the art, it maybe assumed that the parts of the mechanism are in the position indicatedin Fig. 1, the reversing-lever 46 being in vertical position in themiddle of its range of movement and the inlet-valve having no movementin the steam-chest, it being disposed above the inlet-ports 4, as shownin Fig. 6. The engine is therefore standing still. If now it is desiredto set the engine in motion in either direction, the reversing-leverwill be thrown to the end of its range of movement in one direction orthe other in order that the inlet-valve may make its full stroke andadmit a maximum amount of steam to the cylinder upon each movement ofthe valve. 1f the reversing-lever is thrown forward, the rod 30, theframe 47, the link 29, and the arm 28 of the bell-crank carried by theshaft 27 will all travel forward. The link 24 will be lowered, so thatthe slide 22, which moves therein, will lie at the top of the link andthe maximum throw will be given to the frame 16 by the rocker 17 and theinlet-valve 8 will have its full stroke. The casing 35, which is shownat the forward end of the bed 36 in Fig. l, will not be disturbed bythis movement of the reversing-lever 46, as the spring-pressedlocking-bolt 64 at the rear end of the casing will continue to engagewith the aperture in the bed provided for it. If, however, after thereversing-lever is thrown forward it is desired to swing it rearward tothe other end of its stroke or if instead of throwing it forward fromthe position shown in Fig. 1 it is desired to throw it rearward toproduce the opposite movement of the engine, the pin 48, carried by theframe 47 and the rod 30, will move rearward in the slots 49, providedtherefor in the casing 35, and engaging the concavity 62in the arm ofthe rear bell-crank 57 within the casing the said bell-crank will beturned upon its shaft 58 and the horizontal arm 59 of the bell-crankwill be thrown upward, lifting the locking-block 50 against theresistance of the spring 54 until the lug 52 at the bottom of thelocking-block is drawn out of the recess 63, with which the lug 52 hadbeen in engagement. At the same time the movement of the pin 48 underthe bar 66 will cause the elevation of the rear end of the said bar, andthe spring-pressed bolt 64, attached to the rear end of the bar, Will bedrawn upward out of the recess with which it had previously been inengagement. This withdrawal of the lug 52 and the spring-pressed bolt 64from engagement with openings in the bed 36 will occur as thereversing-lever passes the middle point of its swing, and after passingthat point the casing 35 will travel rearward along the bed 36 with therod 30 until the lever 46 reaches the end of its movement, at which timethe spring-pressed bolt 64 at the forward endof the bar 66 will comeinto registration with the forward aperture and will automatically dropthereinto, so locking the casing 35 against any further movement. Themovement of'the casing 35 from one end of the bed 36 to the other duringthe swing of the lever 46 from the middle point of its range of movementto the rear limit thereof causes the link 34 to move rearward to thesame extent, and the arm 33 of the bell-crank carried by the shaft 32 isswung through as great an are as the arm 28 of the bell-crank upon theshaft 27 is turned during the entire swing of the lever 46, as the arms28 and 33 bear the ratio of two to one in length.

From the foregoing description it will be seen that during one half ofthe swing of the lever 46 from one end of its range of movement to theother the pin 48 will move freely along the slot 49, provided thereforin the easing 35, without imparting movement to the casing 35, andduring the other half of the swing of the lever 46 the casing 35 willtravel rearward with the rod 30. it will also be noticed that one halfof the swing of thelever 46 from either end of its range of movement tothe middle point thereof is without effect upon the casing 35, but thatthe other half of its movement imparts to the casing 35 and to thebell-crank arm 33, connected with said casing by the link 34, a movementsufficient to raise the link 25 to change the position of the slide 23from one end of the link to the other, thereby effecting a completereversal of the movement of the exhaust-valve and giving it its maximumstroke in either direction. When the casing 35 has reached the rearwardlimit of its movement and the lever 46 begins to be moved forward towardthe middle of its range of movement to cut down the stroke of theinlet-valve, the locking-block 50 will be depressed by the action of thespring 54 and the lug 52 will enter one of the openings 63 andsupplement the action of the springpressed bolts 64 in retaining thecasing 35 in position. As long as the casing 35 remains stationary nomovement is imparted to the link 25 to vary the position of the slide 23therein, and consequently there is no variation of the stroke of theexhaust-valve.

Briefly summarized, the connection of the reversing-lever 46 with thelinks 24 and 25 is such that the link 24 is moved up and down throughoutthe entire swing of the lever 46 to the rear or to the front, as thecase may be, while the link 25 is moved only during the movement of thelever 46 from the center of its swing to one end thereof, and nomovement is imparted to the link 25 by the lever as it moves from oneend of its range of movement toward the middle thereof.

As the locking devices in the casing 35 are automatically operative whenthe casing reaches either end of its range of movement to hold thecasing stationary until the lever 46 is swung in the opposite directionuntil it passes the middle of its swing, any variation in the stroke ofthe exhaust-valve is positively prevented, as the lever 46 is hooked upafter the engine is started and a considerable degree of speed isdeveloped.

As the reversing-lever is always thrown to the limit of its swing instarting the engine in either direction and is gradually hooked uptoward the middle of its swing after its speed has been developed, itwill be clear that the exhaust-valve is always set for its full stroke,and the reduction of the stroke of the inlet-valve as the lever ishooked up is not accompanied by a corresponding reduction in the strokeof the exhaust-valve with the cutoff of the exhaust. Hence while theamount of steam admitted to the cylinder upon each stroke of theinlet-valve is considerably reduced after the engine is started theexhaust is not correspondingly reduced, and much less resistance isoffered to the advance of the piston under the influence of thefreshly-admitted steam than is offered thereto when the same valveperforms the functions of an inlet and an exhaust valve, making thestroke of the exhaust-valve always correspond to the stroke of theinlet-valve.

l/Vhile l have described and illustrated an embodiment of my inventionin which the strokes of the inlet and exhaust valves are controlled bylink-motions, it is obvious that other devices for varying the strokesof the valves may be employed, and I do not, therefore, limit myself tothe specific structure shown, but reserve the right to make changestherein such as lie within the scope of the appended claims.

Having thus described my invention, 1 claim as new and desire to secureby Letters Patent 1. The combination with a cylinder having inlet andexhaust ports, of separate inlet and exhaust valves, a reversingmechanism for each valve, a reversing-lever common to both reversingmechanisms, and means whereby the reversing mechanism for theexhaustvalve will only be operated during the movement of said leverfrom the center of its movement to the end thereof.

2. The combination with the steam-engine cylinder having steam inlet andexhaust ports, of separate inlet and exhaust valves slidable over saidports, means for reversing the stroke of each of said valves, saidreversing means comprising a movable lever which is constantly connectedwith said inlet-valve, and automaticallyoperative devices for connectingsaid lever with said exhaust-valve intermediate of the ends of thestroke of the lever.

3. The combination with a steam-engine cylinder having inlet and exhaustports, of separate inlet and exhaust'valves co6perating with said ports,and mechanism for reversing the stroke of both of said valves, saidmechanism comprising a lever operative upon the inlet-valve throughoutits entire stroke and connections between said lever and theexhaust-valve, whereby the reversal of the exhaust-valve is accomplishedduring the latter half of the stroke of the lever.

4:. The combination with a steam-engine cylinder having inlet andexhaust ports, of separate inlet and exhaust valves cooperating withsaid ports, separate means for imparting reciprocatory movement to eachof said valves, means for reversing the movement of each of said valves,said means comprising a crankarm for each valve, the crank-arm for theinlet-valve being twice the length of the crankarm for theexhaust-valve, and a lever for imparting movement to said crank-arms,said lever being connected directly with the crankarm for theinlet-valve at all times, and being automatically connected with thecrank-arm of the exhaust-valve during the latter half of its strokeonly.

5. The combination in locomotive valve mechanism, of separate steaminlet and exhaust valves, separate means for imparting reciprocatorymotion to each of said valves, sep arate means for reversing the strokeof each of said valves, the reversing means for the inletvalve beingadapted to vary the stroke thereof, and connections between thereversing means of the inlet and exhaust valves automatically operativeduring the latter half of the stroke of the reversing means for theinletvalve, whereby the reversal of the stroke of the exhaust-valve isaccomplished during the latter half of the stroke of the reversing meansfor the inlet-valve.

6. The combination with a steam-engine cylinder having inlet and exhaustports, of an inlet-valve cooperating with the inlet-ports, a separateexhaust-valve cooperating with the exhaust-ports, mechanism forimparting reciprocatory movement to the inletvalve, means for reversingthe stroke of the inletvalve, said means being adapted to vary thestroke of the inlet-valve, mechanism for imparting reciprocatorymovement to the exhaust-valve, and mechanism for reversing the stroke ofthe exhaust-valve, said reversing mechanism being adapted for automaticconnection with the means for reversing the stroke of the inlet-valvesubstantially in the middle of its movement, whereby the reversal of thestroke of the exhaust-valve is accomplished reversing-lever, and alocking device for locking the exhaust-valve-reversing mechanism duringthe adjustment of the inlet-valve-operating mechanism to reduce thestroke of the inlet-valve.

9. The combination with a cylinder having inlet and exhaust ports, ofseparate inlet and exhaust valves, a reversing mechanism for each valve,said mechanisms having a common reversing-lever, aconnection between thesaid lever and the exhaust-valve-reversing mechanism, whereby the saidexhaust-valve mechanism will be operated intermediate of the ends of thestroke of the reversing-lever, and means for locking the said connectionin position.

10. The combination with separate inlet and exhaust valves, of areversing mechanism for each valve, said mechanisms having a commonreversing-lever, a sliding member loosely connected with thereversinglever, and means for locking said sliding member in position.

11. The combination with separate inlet and exhaust valves, of areversing mechanism for each valve, said mechanisms having a commonreversing-lever, asliding casing having a loose connection with thereversing-lever, and a locking mechanism within the casing for lockingthe said casing in position at the ends of its movements.

12. The combination with separate inlet and exhaust valves, of areversing mechanism for each valve, said mechanisms having a commonreversing-lever, asliding casing having a loose connection with thereversing-lever, and a locking mechanism within the casing andcontrolled by the connection between lever and casing, for locking saidcasing in position at the ends of its movements.

13. The combination with separate inlet and exhaust valves, of areversing mechanism for each valve, said mechanisms having a commonreversing-lever, a sliding casing, having slotted sides, a pin carriedby the lever and working in the slots of the casing, a spring-pressedlocking member in the casing, and bell-crank levers in the casing andeach having one member engaging the locking member and the otherextending into the path of the pin connecting the casing and lever.

14:. The combination with separate inlet and exhaust valves, of areversing mechanism for each valve, said reversing mechanisms having acommon reversing-lever, a support provided with openings, a slidingcasing on said support and having slotted sides, a pin carried by thereversing-lever and working in the slots of the casing, a spring-pressedblock having a projection on its bottom for entering the openings of thesupport, and bell-crank levers in the casing and each having one memberengaging the block and the other extending into the path of the pinconnecting the lever and easing. 4

15. The combination with separate inlet and IIO exhaust valves, of areversing mechanism for i the path of the pin connecting the casing andeach valve, said mechanisms having a common reversing-lever, a sup portprovided with openings, a sliding casing on the support and havingslotted sides, a pin carried by the reversing-lever and Working in theslots of the casing, a spring-pressed block in the casing and providedwith a projection engaging openings in the support, bell-crank levers inthe casing and each having one member engaging the block and its othermember extending into lever, spring-pressed bolts in the casing andentering openings in the support and a bar connecting the upper ends ofthe bolts.

In testimony whereof I have signed my name to this specification in thepresence of tWo subscribing Witnesses.

FRANK ELI SMITH.

Witnesses:

G120. R. FRYER, EDWIN J. BROWN.

